1. Field of Invention
This invention relates in general to satellite navigation systems and in particular to mitigating the effects of CW interference in Global Positioning System (“GPS”) receivers.
2. Related Art
Satellite positioning systems have been deployed that enable receivers to determine their position on or near the Earth. These satellite positioning systems typically have a number of satellite vehicles (SVs) that orbit the earth providing time and other data using spread spectrum approaches, such as CDMA in the GPS system deployed by the United States.
One major advantage of a spread spectrum system, such as a system that includes a GPS receiver, is its ability to reject interference such as wide band interference. This is because correlation of a wide band interference signal with a reference code reduces the power density of the interference and its effect on the signal. However, it is also known that GPS receivers are susceptible to narrowband interference. One common type of narrowband interference is continuous wave carrier (CW) interference. In fact, the narrower the bandwidth of the interference signal the less is the ability of the receiver to reject it, resulting in degraded performance such as reduced receiver sensitivity.
Past methods of suppressing narrowband interference have included hardware detection and mitigation of interference in the frequency domain or in the time domain. However, hardware interference suppression methods introduce increased hardware complexity and cost, and may degrade receiver sensitivity when no interference signal is present or may suffer from poor performance in a dynamic interference environment.
Therefore, there is a need for a system and a method capable of mitigating the effects of CW Interference via post correlation processing in a GPS Receiver.